The present invention relates generally to window sash balances, and more particularly, to window sash balances having improved components and subassemblies forming parts thereof.
The invention provides components which are adapted for more economical and rapid manufacture, simplified assembly, and greater reliability in use. The components provided by the invention also have other desirable characteristics, including ease of positioning for installation.
Substantially all windows which open vertically, including both so-called single-hung and double-hung windows, use a balance apparatus of some sort to insure that the window sash will remain in the position in which it is placed by the person manipulating it. While certain low cost window assemblies rely only on friction to maintain the sash in a desired position, the better window assemblies include a balance for this purpose. The balance serves to reduce the effort required to open and close the window, and to move it to a desired position where it will remain supported by the balance.
A number of different types of window balance systems are currently in use, including older systems relying merely on counterbalance weights affixed to the ends of chains or ropes and trained over stationary pulleys. However, with the advent of modern original equipment and so-called replacement windows, there has been a demand for windows which contain high quality balances and which are also capable of ready removal, either partial or complete, from the accompanying window jambs. For example, many windows of today are able to be tilted out of the jamb channels in which they are received for purposes of cleaning. Still other windows are able to be totally removed by a variety of different mechanisms.
Windows of this type must rely on balances which are substantially self-contained. Balances which are suitable for windows of this type tend to become more sophisticated in construction, and have been characterized by the imposition of more exacting standards. In the meantime, there has been a demand for window sash balances and components which are able to be manufactured easily, and which are highly reliable and long lasting in use. Some known window sash balances provide a number of advantages, but these balances include block and tackle or pulley block assemblies which must undesirably be made individually for each set of balances. In such constructions, a pulley block is literally formed around the pulleys after the pulleys are positioned in a machine or the like.
In such constructions, the axles supporting the pulleys are staked or riveted in position after a metal housing is formed and wrapped around one or more pulleys in an operator-controlled machine operation. In such a case, the assembly of pulley blocks or sheaves has required the attention of an individual operator in each stage of manufacture, and accordingly, such designs are not readily subject to automated manufacture.
In addition, other pulley block assemblies of this type are, because of their method of manufacture, made from aluminum or steel. In such cases the possibility of undesirably high friction levels existing between the side plates of the pulley blocks and the balance frame channel constitutes a drawback of the balance assembly. This is particularly true because, where a coil type spring is used, there must be minimal working clearances between the sides of the pulley block and the interior surfaces of the frame channel to avoid undesirable torsional rotation of the block assembly.
In certain cases, the balance is called upon to support considerable weight, and this in turn calls for pulley supporting axles of significant diameter. As the diameter of the pulley supporting axles increases, the ability to form riveted or flatened heads on the axles easily and at low cost is diminished.
Because balance assemblies of the type with which the invention is concerned are sometimes utilized in unusual positions, or are assembled differently for special purposes, it is also desirable to have a pulley block which is symmetrical in one or more planes, and in which, therefore, either end may be used interchangeably. It is also desirable that the surfaces made in forming the balance pulley block not present sharp corners or radii which limit the ability of the balance to receive a cord or other unit, inasmuch as such sharp edges subject the cord to wear by fraying or the like.
In view of the foregoing and other drawbacks and disadvantages of known types of window sash balances and components thereof, it is an object of the present invention to provide an improved sash balance.
A further object is to provide a sash balance which includes a pulley block component having a number of desirable advantages and characteristics.
Another object is to provide a pulley block assembly for a block and tackle type window balance in which the block itself may be manufactured in a single, relatively simple, high production operation, such as by injection molding the same from a moldable resinous material.
Another object is to provide a sash blance which includes components thereof which are readily adapted for automated or semi-automated assembly.
Still another object is to provide a pulley block for a window sash balance unit wherein the block contains certain reference surfaces which enable the pulleys to be positioned in a desirable position in the block without sacrifice of the working clearances needed for operation of the blanace.
A still further object is to provide a unitary block assembly which is adapted to receive a set of two pulleys in one portion thereof and a single pulley in another portion thereof, and which includes guide surfaces adapted to facilitate positioning of pulleys within the block prior to assembly.
Yet another object of the invention is to provide a block and tackle assembly which includes specially designed pulleys adapted for easy, economical positioning within a pulley block.
Another object is to provide a block and tackle assembly in which the pulleys include beveled or tapered axle-receiving portions and in which the axles include beveled or tapered end portions, both tapers thus providing pilot diameters to aid in assembly of the unit as a whole.
A still further object is to provide a pulley block unit for a sash balance assembly which includes a tapered pilot or guiding surfaces to assist positioning the axle within the pulley block during assembly thereof.
A still further object is to provide a window sash block and tackle assembly which includes a pulley block having additional guide surfaces for aligning the hook or other cord attachment means so as to position the same for easy reception by a slot in the jamb channel of the window assembly.
A still further object of the invention is to provide a one piece, pre-formed pulley block assembly which includes assembly reference surfaces and guide members positioned so as to add strength to the assembled pulley block, and to provide clearance for the cords or tackel used to support the block and the pulleys received therein without interfering therewith in use.
A still further object is to provide a pulley block assembly which is capable of achieving the foregoing and other advantages in use, and which uses the minimum material required consistent with possessing the requisite strength.
Another object of the invention is to provide a pulley block assembly which uses large diameter axle units which are readily positioned and assembled, and which include pilot surfaces arranged so that the axles may be inserted into the block from either side thereof.
A still further object is to provide a pulley block assembly which is symmetrical for purposes of installation along one or more planes, but which still retains characteristic end portions for proper assembly.
The foregoing and other objects and advantages of the invention are achieved in practice by providing a pulley block assembly which includes a frame and surfaces defining a pulley-receiving slot therein, a pulley receivable in the slot, and an axle adapted to extend through an opening in the sidewalls of the block and to support and position the pulley therein, with such units including assembly reference or guide surfaces and various tapers or bevels adapted to permit positioning of the parts for assembly merely by placing them in the desired position against a reference surface and inserting the axle through the opening provided.
The invention is also carried into practice by providing a pulley block assembly which includes guide surfaces for directing the pulley into the pulley-receiving opening, and which may further include surfaces for positioning the hook by reason of engagement between a portion of the guide surfaces and one side of the hook when the balance assembly is positioned for installation.
The manner in which the foregoing objects and advantages of the invention are carried into practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the invention set forth by way of example and shown in the accompanying drawings, in which like reference numerals indicate corresponding parts throughout.